Channel changer for use in a switched digital video system

• US 6,728,965 B1
• Filed: 08/20/1997
• Issued: 04/27/2004
• Est. Priority Date: 08/20/1997
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Next Level Communications, Inc. (Motorola Solutions, Inc.)
• Inventors: Mao, Weidong
• Primary Examiner(s): Srivastava, Vivek
• Application Number:
  US08/915,467
• Time in Patent Office: 2,442 Days
• Field of Search: H04/N.100, H04/N.300, H04/N.5445, H04/N.5266, G06/F.300, G06/F 1.300, 395/200.47, 395/200.48, 395/200.49, 395/200.17, 348/6, 348/12, 348/13, 348/10, 348/513, 348/523, 348/525, 348/526, 348/731, 348/705, 455/3.1, 455/4.2, 455/5.1, 455/6.2, 455/5.6, 370/422, 370/477, 370/509, 370/510, 725/125, 725/105, 725/116
• US Class Current: 725/38
• CPC Class Codes: H04N 21/426 Internal components of the client ; Characteristics thereof H04N5/44 takes precedence
• CPC Class Codes: H04N 21/4384 involving operations to reduce the access time, e.g. fast-tuning for reducing channel switching latency
• CPC Class Codes: H04N 5/50 Tuning indicators; Automatic tuning control
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

A rapid channel changer for use in a digital broadband access system. The subject rapid channel changer includes a cache buffer for storing the video data and a processor for detecting and pointing to the synchronization frames. When a subscriber'"'"'s channel change request is received by the processing unit, the corresponding video signal can be quickly accessed and directed downstream to the subscriber, since the processor can immediately synchronize the video data without having to wait for the next synchronization frame.

Claims

1. A method of switching to a video channel requested by a subscriber in a switched digital video system, said method comprising:

inputting video data corresponding to a plurality of video channels into a first memory means, the video data including a continuous stream of a predetermined number of consecutive data frames, wherein one of the stored data frames is a synchronization start point;

detecting a location of the synchronization sort point stored in the first memory means for each input video channel

recording the locations of the detected synchronization start points in a second memory means;

receiving a request for a video channel from a subscriber;

accessing the continuous stream of video data corresponding to the requested video channel at the synchronization start point location recorded in the second memory means; and

transmitting the accessed continuous stream of video data corresponding to the requested channel to the requesting subscriber;

wherein the fist memory means is a “

first-in-first-out”

type cache buffer.

2. The method of claim 1 wherein the video data is in an MPEG-2 format.

3. The method of claim 1 wherein the accessed stream of video data is multiplexed with other video streams for transmission to a plurality of subscribers.

4. The method of claim 1 wherein, after receiving the video channel request, the method further comprises the step of acknowledging said request.

5. A channel changer for use in a switched digital video system, the digital video system receiving video data corresponding to a plurality of video channels, the channel changer comprising:

means for storing the video data, the video data including a continuous stream of a predetermined number of consecutive data frames, wherein one of the stored data frames is a synchronization frame;

means for indexing the stored synchronization frame and another synchronization frame included in video data of at least one other vide signal;

means for accessing the continuous stream of video data at the synchronization frame; and

means for transmitting the accessed continuous stream of video data to a requesting subscriber, wherein the means for storing is a video-data buffer memory, wherein the means for indexing is a processor and wherein a means for storing the current location of the synchronization-frame is a synchronization-frame buffer memory.

6. The channel changer of claim 5 wherein the received video data is in a compressed format.

7. The channel changer of claim 5 wherein the received video data is in MPEG2 format and the synchronization frame is an intracoded frame.

8. The channel changer of claim 5 wherein the buffer memory is a “

first-in-first-out”

type buffer memory.

9. The channel changer of claim 5 further comprising:

means for receiving a request for video data from the subscriber; and

means for acknowledging the request.

10. The channel changer of claim 5 wherein the digital video system comprises a broadband digital terminal (BDT) for receiving the video data.

11. The channel changer of claim 5 wherein the digital video system comprises a broadband network unit (BNU) for directing the video data to a plurality of subscribers.

12. A method of switching to a video channel requested by a subscriber in a switched digital video system, said method comprising:

inputting video data corresponding to a plurality of video channels into a buffer memory, the video data including a continuous stream of a predetermined number of consecutive data frames, wherein one of the stored data frames is a synchronization start point;

detecting a location of the synchronization start point stored in the buffer memory for each input video channel

recording the locations of the detected synchronization start points in a memory receiving a request for a video channel from a subscriber;

accessing the continuous stream of video data corresponding to the requested video channel at the synchronization start point location recorded in the memory means; and

transmitting the accessed continuous stream of video data corresponding to the requested channel to the requesting subscriber.